Consideration and Adoption of Resolution No. 2025-10 and Ordinance No. 2025-04: An ordinance to revise the Stormwater Management Design Manual to comply with current standards, definitions, and engineering design by adopting the 2025 Stormwater Management Design Manual.
 

1. Adopt Resolution No. 2025-10
2. Read Ordinance No. 2025-04 by title only for the final time
3. City Clerk reads Ordinance No. 2025-04 by title only (if approved above)
4. Adopt Ordinance No. 2025-04

The 2025 Stormwater Management Design Manual has been developed to assist in the design and evaluation of public and private stormwater management facilities within the boundaries of
the City of Flagstaff. Stormwater management policies, design procedures, and design criteria are presented within the manual for conducting hydrologic and hydraulic studies, designs, and
evaluations. 

The overall goals for the development of this manual are to:

• Ensure compliance with applicable floodplain and stormwater management regulations, policies, and design criteria
• Minimize public expenditures for drainage projects
• Minimize the review time of drainage report and/or grading and drainage plan submittals
• Provide consistent policies and criteria that will result in uniform practices and drainage infrastructure within the City of Flagstaff
• Improve the water quality of stormwater runoff within the City of Flagstaff

The current Stormwater Management Design Manual was adopted in 2009 and contains standards that need to be updated, engineering design, and policy. This update was contracted by the Stormwater Section to Woodson/Ardurra and is largely based on current drainage plans by ADOT, Maricopa County, and Coconino County. Engineering peer-review was provided in the spring of 2024 with comment resolution in summer of 2024. A public comment period was initiated after the September 19, 2024 Water Commission presentation of this draft revision. Public comments are also addressed in this revision.

Project Name: COF Stormwater Management Drainage Design Manual revision
Cost: $88,500
Account Number Budgeted: 206-08-331-1251-0-4206
Funding Source: Stormwater Utility

This revision will bring the City on-par with most municipalities in the region. The current manual is 16 years old and is in need of update.

High performance governance: Serve the public by providing high quality internal and external customer service (SP)1.2/ 3.2/ (RP)ED.1
Safe & Healthy Community: Foster a safe, secure, and healthy community (SP)3.4/ 4.1/(RP)PF.1/ PF.3
Sustainable, Innovative Infrastructure: Deliver outstanding services to residents through a healthy, well-maintained infrastructure system (SP)3.2/ (RP)PF.2/ E.1-2/ WR.1-6/ LU.7-8/ CD.1/
T.4-6/ REC.1
Environmental Stewardship: Implement sustainable building practices and alternative energy and transportation options (RP)E&C.6/ E.1-2/ WR.3/ PF.2/ REC.1/ LU.5/ LU.10/ LU.13-14/ LU.18/ T.3-7/E&C.2

Carbon Neutrality Plan
Community resilience, CR-1 and CR-2

Regional Plan
Goal E&C.3. Strengthen community and natural environment resiliency through climate adaptation efforts.
Goal WR.5. Manage watersheds and stormwater to address flooding concerns, water quality, environmental protections, and rainwater harvesting.
Goal ED.1. Create a healthy environment for business by ensuring transparent, expeditious, and predictable government processes.

Recommended action:

Adopt Resolution 2025-10 and Ordinance 2025-04 with the revisions in the 2025 Stormwater Management Design Manual.
Alternative 1: Deny adoption of the resolution and ordinance with the revisions in 2025 Stormwater Management Design Manual and retain the 2009 manual.
Alternative 2: Provide further revisions to the updated 2025 Stormwater Management Design Manual, which will delay adoption and may add cost to the project.

The original Stormwater Management Design Manual was adopted in 2001 and revised in 2009. The manual is intended as a guide for stormwater best practices for new development. The draft revised version was created by Woodson/Ardurra over the last year based on current design manuals from Maricopa County, Coconino County, and ADOT.

Priority Based Budget Key Community Priorities and Objectives
Safe & Healthy Community: Ensure the built environment is safe through the use of consistent standards, rules & regulations, & land use practices

Regional Plan
Goal WR.5: Manage watersheds and stormwater to address flooding concerns, water quality, environmental protections, and rainwater harvesting.
Goal T.21: Improve transportation safety and efficiency for all modes.

This project has no nexus with the CNP.

This project has no significant nexus with the 10-year housing plan.

This supports both the 2025 Water Services Division Plan and the 2028 Stormwater Section Plan.